Apparatus for lapping quartz oscillator plates



April 15, 1947. A l. s. PRIMUS 2,419,033

APPARATUS FOR LAPPING QUARTZ OSCILLATOR-PLATES 'Filed April 6, 1945 3 Sheets-Sheet 1 INVENTOR IRVING 5. FR) M US April 15, 1947. s, Us 2,419,033

' APPARATUS FOR LAPPING QUARTZ OSCILLATOR PLATES Filed April 6, 1945 3 Sheets-Sheet 2 {f'm l3, {:3 50 lilllllllli 7 5;; T x 75 INVENTOR IRVI N6: 5. PRIMUS ATTORNEY April l5, 1947. s, PRIMUS 2,419,033

APPARATUS FOR LAPPING QUARTZ OSCILLATOR PLATES Filed April e, 1945 s Sheets-Sheet a INVENTOR RVING! 5.PRH"-IUS B r' ATTORNEY Patented Apr. 15, 1947 APPARATUS FOR LAPPING QUARTZ OSCILLATOR PLATES Irving S. Primus, New York, N. Y., assignor to Reeves-Ely Laboratories. Inc., New York, N. Y., a corporation of New York Application April 6, 1945, Serial No. 586,952

4 Claims. (Cl. 51118) This invention relates to new and useful improvements in the manufacture of quartz oscillator plates and has particular relation to improvements in the method of and apparatus for lapping such plates. Various methods and constructions of apparatus have been suggested for use in the lapping of blank quartz oscillator plates to bring them safely to a thickness from which they can be hand-finished with a minimum of effort. While highly useful in many cases, these previous proposals have certa n inherent disadvantages. When using them the plates may be lapped unevenly on their major faces so that such faces are not brought into substantially true paralelism; and/or their major faces and edges are not lapped smooth; and/or the amount of lapping is not accurately controlled; and/or an undue amount of time is required; and/or plates are damaged in large numbers during the lapping operation, etc.

As a result of my investigations, I have discovered certain improvements in the lapping of blank quartz oscillator plates which substantially eliminate disadvantages of the character enumerated.

Using my invention quartz oscillator plates may be easily, smoothly, qu ckly and accurately lapped a predetermined amount; and after the plates are lapped, they may be hand-finished with a minimum of effort.

In accordance with the invention ,a number of blank quartz oscillator plates are simu'taneously lapped by moving them in spaced relationship to on another between two lapping surfaces in a suspension of abrasive grit. About a fixed-stationary point one of the lapping surfaces is rotated in contact with a major face of each blank plate while the other lapping surface is maintained substantially stationary and in con-tact with the other major face of each blank plate.

While maintained in spaced relationship to one another the blank plates are moved in an undulating satellite path of relatively large convolutions. Such path is around the above mentioned fixed-stationary point and is relatively far removed from the center of each blank plate. The direction of movement of the blanks is generally opposite to that of the rotating lapping surface, so that the major faces of the blank plates are lapped as they are repeatedly passed completely around, and across the effective lapping surfaces. In addition, while still maintained in spaced relationship with one another, the blank plates are moved in an undulating path. of relatively small 2 convolutions about a moving point relatively near their respective centers.

To this end, the invention contemplates apparatus including a pair of juxtaposed lapping heads, means for rotating one of the lappin heads about a fixed-stationary point, and means for holding the other lapping head substantially stationary. A carrier-disc is disposed between the lapping heads, the disc being provided with a plurality of spaced openings each of which is adapted freely to receive a blank oscillator plate. Means are provided for moving the carrier-disc in a satellite path about the fixed-stationary point and about a fixed-moving point that is relatively far removed from the centers of the disc openings and moves in a circular path about the fixed-stationary point, so that blank oscillator plates in the spaced openings of the carrier are made to follow a tortuous path around and across the lapping surfaces of the lapping heads.

In a presently preferred practice of the invention, the lapping heads are horizontally disposed, one above the other, and the carrier-disc is positioned between the two lapping heads. The lower lapping head is rotated around a fixedstationary point while the upper lapping head is maintained substantially stationary. Means is provided for rotating the carrier-disc about a fixed-point that in turn moves in a circular path around the above mentioned fixed-stationary point. The openings in the disc are generally polygonal, and preferably pentagonal, in shape, with their sides curved inwardly.

As a result of the construction employed, blank oscillator plates confined within the openings in the carrier-disc are made to follow an exceedingly tortuous path between the grinding surfaces of the lower and upper lapping heads. This causes substantially even, smooth grinding or lappins of all the blank plates. By the time the operation is over, all of the plates are lapped to is rotated as well as around its own moving point. Lapping of each plate within its disc opening is not only facilitated by this series of compound movements but th point-to-point contact of each plate with the inwardly-curving sides of its disc opening tends greatly to reduce chipping or breaking of edge and corner portions of the plate.

Other" features of the invention will become apparent from a consideration of the following detailed description taken in connection with the accompanying drawings wherein. a satisfactory embodiment of the invention is shown How-- ever, it is to be understood that the invention is not limited to the details disclosed but in cludes all such variations and modifications as fall within the spirit of the invention and the scope of the appended claims.

In the drawings:

Fig. 1 is a side elevational view with theupper portion partly in section, of an apparatus illustrative: of-a'. practice of: the invention Fig. 2 is a sectional viewomthe. line 2;=-2: of Fig. 1;

Fig; 3 is: a. sectional view cm the: line 3:--3- of" Fig; t is a sectional-view on the. line: i of Fig. l; and

Fig. 5 is an enlarged: view. showing. thezlapping head and lower p ortiorrof theapparatus in:sec-- tion.

Referringifirst"toFig. l, the apparatus shown comprises a base tllintegrally formed. with a plurality oi? vertical: supports H. A lower drive motor l2: is-securedto the base. by a. motor support I Za. including two parallel bar-l ke portions l-3 adiusta-bleinwardly and outwardly of. a hearing M at one side of the. base. Following any adjustment" the-posi-tiom of. the motor. is fixed. on. tightening ot a; set screw 35. Theimotor is. pro vided with a. drive shatt. I-6=on the outer: end of which: is' secured a motor pulley l-l connected to: a variable speed pulley It. byabelt. l9". The variable speed pulley isrsecured' to the lower end of: a lower spindle extending vertically (see Figs. 1 and 5)- through-a bearing securing collar 2:], bearing sleeve 22, sleevefsupport-fi's, lock: nut 2.4, and'support collar 25.

Bearingsecuring collar 24: is threaded'into-the lower end. oi sleeve 22.. A thrust bearing 2% is mounted: about spindle 2!! within thelower por. tion. of bearing sleeve: 22'. Sleeve support 2-35 is secured: to bearing sleeve. 22" by a: set screw 28. The upper portion. of. the sleeve; support 23- includes an annular flange 29' secured against the top; side of base til by a plurality of. set. screws 39.. An upper thrust bearing 3+ ismounted about the spindle 2-0 within the upper end portion of bearingsleeve 22.

To prevent ingress. of. abrasive; material or other foreign: particles, the upper portion of; sleeve 22 is. covered with a. bearing-shield? 3% fitting loosely about the sleeve; The; upper portion of the bearing-shield? is' carried. inwardly providing an internally threaded annulus 33 disposed: on the upper surface of a horizontal shoulder or enlargement 34- of. a threaded. bushing- 3 5 fixed to spindle 20 by a set-screw 3t. Thenut 24. is screwed onto the threaded. bushing; and bears downwardly on annulus 33 to: assure a tight fit. construction is: more fully described. and claimed my co-pending application Serial No. 586,953,. filed April 6, 1945.

At-i-ts upper end-spindle Ell includes a tapered portion 40! having; a wedge fitv in. the; internally tapered collarv 25. The: lower portion of. the sup port collar stops directly above nut 24, threaded bushing 35 and the reduced portion of spindle 20. Support collar includes a radial flange 44 mounting a horizontally disposed support 43. These parts are secured together by means of a plurality of screws 44a. A lower rotating lapping block d5 isSGGUI Ed against tha'upper side of the horizontal" support 43 by" means of a plurality of III a verticali column 5|.

screw 46 passing through the horizontal support and entering the lapping block from its under side.

Referring again to Fig. 1, base Ill is provided at one side with a vertical hollow socket 50 in which; is: securely fitted the lower end portion of A bracket-housing 52 is securedto the upper end of the column by means of.-a.set. screw 5.3. An upper drive motor 54 is secured to the bracket-housing by a motor support 55h. having a laterally extending bar-like part 55 fitting in an outwardly extending bearing; 56. at one SidEzQf. therbracket-housingc Hart 55 is shiftablelongitudinally in the bearing. 55 whereby theeposition of the motor. is laterally ad'.-- jyustable. Aset'screw- 5:7;is providedlto secure part 55 and thus the motor 54 in. adjusted. position; On. the outer end of shaft 58: of. motor. 54 issecured a motor pulley 59,. adapted to. drivea; pulley 60 througha belt.6 l- The pulley fillismounte ed on an idler shaft: 6 2, the lower. end. portion of. which fits into a vertical. bearing. 63 secured to the. bracket-housing. as-by bolts 64.. Also, on shaft- 62 to. be driven. therewith is. a variable speed. pulley 60a.

Variable: speed pulley 6.0a is connected by a belt. 6.6:- to drive a. variable. speed spindle pulley 55 secured to the outer. end portion of. an upperspindle 61-, in axial. alignment with. the; lower spindle 2 0.. Spindle 6:1 passesrthrough' a sleeve; 88 operatively connected to. the spindle by a key 69. secured to the. sleeve. and slidably positioned. within a spline extending a substantial dis;- tance up. and downthe spindle. A pair of. bearings H. and 1.2 is disposed. between. the. sleeve 68' and abuilti-in bearing. l3. within. the upper portion of the bracket-housing, 5.2. About the lower section ofthe spindle li'lisv a quill. 15. ex--- tending through an opening in the lower. portion of'the bracket-housing; Bearings. l6 and ll. are disposed between theupperand lower endsof. the quill, respectively; and the spindle 6.1.

The quill I5 is provided with a vertical rack section 18 meshing" with a pinion 79 secured. to a shaft" 80 extending completely through the bracket-housing 52* (see Fig. 4). Collars. 8i and 82' are secured to the shaft 89 at the respective outer sides of the bracket-housing 52, to keep the shaft from longitudinal movement while. a knob 8-3 provides for hand-turningv of the shaft to rotate pinion T3 and thereby' raise or lower the quill 15 to adjust it" to the desired positions. As shown in Figs. 1 and 4:, a smallclamp handle 85" is secured to one end of an eccentric shaft 86, extending completely through the brackethousing 521 Shaft 86' is so mounted. that when; turned to one position it is free of quill I5 and when turned to the opposite position binds against said quill to lock the same in any desired position. of adjustment.

Returning to Fig. 1, collars stand 91 aresecured to upper spindle 61 immediately above and below the respective ends of the quill 15'. Therefore, as the quill is adjusted upwardly or down- Wardlyon turning of the knob 83' upper spindle 61 is moved upwardly or' downwardly, the key 69; remaining hithe -spline orkeyway 1B. The

plate I26 and yet 1 on its major faces. Opening I25 are so spaced from the perimeter ofthe disc with. respect to the pin 94 and crank arm 92 that portions of a xnumber of successive openings extend beyond the 5 lower end of spindle 61 is provided with a crank arm 92 secured thereto by a set screw 93 (see Fig. 5). A pin'94 is secured to the far end of the-crank arm and immediately below the latter is received in a hub 95. The lower end of pin 94 fits loosely in a hub 96secured to the central portion of a carrier-disc 91. Hub 96 has a reduced diameter lower end portion which extends through one or more upper washers 98, the center hole of the disc 91, one or more lower washers 99 and is threaded to a lock nut I00. I a As more particularly shown in Fig. 5, carrierdisc 91 is located between the lower lapping head 45 and an upper lapping head I05. Each lapping head is in the form of an annulus the lower head having a central circular opening I06 and the upper head having a similar opening I01. The head openings are in alignment and are sufficiently large to accommodate pin 94 and hubs 95 and 96 as they are moved around by the crank arm 92. 1 Upper lapping head I05 is provided with a plurality of spaced wells I08 (see Figs. 2 and 5), which are funnel-shaped to receive abrasive mixtures, grinding compounds, cleaning fluids, etc. Lift handles I09 and H are secured to the upper lapping head and are adapted to be engaged by a pair of hooks III and H2 pivotally connected to eyebolts H3 and H4 carried by alignment brackets H5 and H6 secured to the top of base I0. An additional pair of opposite alignment brackets Ill and H8 are secured 'to the top of base I0. The brackets are so arranged as to keep lapping head I05 in substantial alignment with lapping head 45, and yet permit the former to float freely within relatively narrow limits.

An apron I20 extends completely around the lapping heads, as more particularly shown in Figs. 1 and 2. The apron may be cast with the base I0 and is sufficiently high to form a receptacle I2I for catching used abrasive mixtures and cleaning fluids laterally discharged from between the lapping heads. 9

Each lapping head is provided with a grinding surface, the surfaces facing but not being in contact with one another when in operation due to the carrier-disc 91 being located between them.

perimeter of the lapping heads in any position or the disc. The portion of each opening so extending is regulated in amount so that the main portion of each blank plate continues to rest between the lapping heads and cannot drop through the opening into receptacle I2I.

This is illustrated in some detail in Fig. 3, which shows five (5) of the openings extending in varying amounts beyond the perimeter of the lower lapping head 45. This permit abrasive mixture from each opening to be discharged laterally and outwardly of the perimeter of the lower lapping head into receptacle IZI as movement of the carrier-disc exposes a portion of the opening beyond the perimeter of the lapping head 45. To this extent each opening is self-cleaning.

Referring to Fig. 2, the apparatus is shown diagrammatically with a manually operated rheostat switch I for drive motor I2, a similar manual operating rheostat switch I3I for drive motor 54, a 3-po1e safety switch I32 and an automatic timing switch I33 for controlling automatically the time period during which a set of oscillator plates is lapped when the apparatus-is in operation. Since the electrical circuits are more or less standard or conventional, they are-not shown in the drawings.

The safety switch connects with electrical current service lines as well as with the timing switch and the two relay switches. During normal operations, current for the two drive motors passes through the timing switch andthe two relay switches. When the apparatus has been operated a predetermined length of time, the timing The grinding surface portion of each head is provided with a plurality of spaced cries-cross grooves I22 (see Figs. 3 and 5) extending through the peripheral edges of the respective heads. These grooves are sufficiently wide and deep to receive and ultimately discharge abrasive mixtures employed in lapping the blank oscillator plates.

. The carrier-disc is more fully shown in Fig 3. It is preferably made ofthin sheet metal, aluminum for example, and has a. diameter substantially the same as that of the lapping heads and is somewhat thinner than the'thickness to which the quartz oscillator plates areto be lapped. Carrier-disc 91 is imperforate except for a plurality of spaced openings I25 extending completely around the disc. and located toward the outer edge thereof. In the instant construction each opening is generally pentagon in shape and has its sides or edgescurved inwardly as shown.

Additionally each opening is of such size as to accommodate but a single blank quartz oscillator permit of turning of the plate switch automatically stops the flow of current, through the relay switches, to their respective drive motors. Further movement of the lower lapping head and the carrier-disc is then terminated.

The apparatus may be operated as follows:

A small amount of a suspension of abrasive grit mixture is placed on top of the lower lapping head 45 and spread substantially evenlyover its lapping surface as well as filling the grooves I22. Carrier-disc 91 is then placed on the lower lapping head, a portion of the disc extending beyond the perimeter of the head, as shown in Fig.5, for example, so that the hub 95 is approximately in a position to receive the pin 94 when crank arm 92 is moved over the hub. A blank oscillator plate I26 is placed in each pentagon opening I25 in the disc. The blank plates are placed in successive disc openings in random positions as in Fig. 3.

A further amount of abrasive grit suspension is placed on the disc 91 and oscillator plate blanks. Upper lapping head I05 is then placed carefully on top of the disc and oscillator plate blanks, hooks III and H2 being engaged with lift handles I09 and IIO. Knob 83 is suitably turned to operate pinion i9 and the latter meshing with rack I8 the quill I5 is moved downwardly, so that pin 94 is dropped into the hub 96 of the disc 91. Handle 85 is brought down to have shaft 86 engaged and clamp the quill in the desired position.

Upper spindle 51 is then turned slowly by hand to move the disc 91 and. give the operator an opportunity to observe whether the blank plates are correctly positioned in the pentagon openings as the protruding portion of the disc moves around the perimeter of the lapping heads. Abrasivegrit suspension is poured into Wells I08 in order to provide a generous supply between the lapping surfaces of the lapping beads.

- Timing switch I33 is set and current passed to drive'motors l2 and 54.. Lower lapping head 45 and. carrieredisc 91.- are. then suitably moved: or. rotated. to; obtain the desired lapping action. on the major faces of the oscillator plates, A: fewtria-l runs. may be made to determine a definite relationship between the: lapping time: and the amount of quartz removed from each oscillator plate. After thisperiod of time has been. deter-- mined for oscillator plate blanksof a certain general-size and. thickness, timing, switch I33 may be adjusted accordingly. When the. time interval expires, current flow to the motors is automatically stopped by the timing switch I33 and this, in turn stops movement or rotation of the lower. lapping-,- head 45' and the carrier-disc 9.1-.

During. thev lapping operation, further amounts. oi. abrasive grit suspension: are fed into wells H18. Due. tothedepth. and. criss-cross arrangement of grooves; I22, spent or partially spent abrasive grit suspension finds: its way to the perimeters of the two: lapping heads and: is. dropped into receptacle Ill... A certainamount' of: the'abrasive grit sus-- pensionin disc. openings. :25 is also dropped. into the receptacle when-a portion of each opening is advanced tothe. point. where. it extends over and beyond-the perimeter of the lapping heads.

It is better practice to rotate the lower lapping head much more rapidly than the carrier-disc. The invention has been. satisfactorily practiced by rotating the? lower lapping head. atthe rate of about 1100 E: P; M. and upper spindle 61 which. turns crank arm 92 and hence moves-pin 94 as wellaas the carrier-disc at the rate of about 90 R-lB; M. With drive motors of adequate speed, the' desired speed relationshipbetween head: 45. anddisc: 91- may be; obtained by using belts i9, 51 and; E6- on the" proper pulleys of; variable speed. pulley 1:8;60 and. 65,, respectively.

If the course of each blank plate I26 is followed. in itsmovements generally toward and away from as. well. as: around; the axis of lower spindle 20. (referred to. as av fixed-stationary point, about which. lower" lapping head rotates, and about whichcarrier-di'sc 91 is moved) and: around the axis. of eccentrc pin- 94 (referred to as' a fixedniovin-g point) about. which carrier-disc 9'! ro-- tates; as: well as its movements generally in its discopening' l-,it.willbe seen that the-blank plate follows. an exceedingly tortuous" path, which brings it-into repeated sliding and turning, contact with: substantially all effective lapping portions of the lapping: surfaces ofthe two lapping heads.

Referring again toFig'. 3, it will be seenxthat. as pin 94 moves in a clockwise direction, indicated by arrows, its. fixed-moving point follows a circular path 136' about the fixed-stationary point [31 of lower lapping head. 1-5. This causes each blank. plate to move inwardly and outwardly across the lapping surfaces. of both lapping head's. whileit progresses. in an undulating: counter-clockwise satellite path completely around fixed stationary point I31 and: counterclockwise completely aroundfixedz-moving point mt.

The'cloc'kwise movement of. the carrier disc is, of course, dueto theclockwise direction of. movement of the eccentricrpin and thecombined counter-clockwise direction of the carrier-discv (and. hence of the blank plates) is; due. to. the dragging action of'the lower lapping head. against. the bottom .of'eachblank plate. as it,.the lapping head rotates, in acounter-clockwise direction. This.

counter-clockwise movement of the carrier disc.

is possible since the pin. 94 has. only a loose lit in; the-huh 926.. The efiect, therefore; is to. move 'etc'., of the grit used.

eachblank plate generally in thefsamedirecti-onsof travel as that of. the rotating lapping surfacein a path of relatively large convolutions aboutv a fixed-moving point that is relatively farremoved from the center of the blank plate and. that: moves in. a generally circular path about the fixed-stationary point of the rotating lapping surface.

In addition to thecounter-clockwise move ments just described, each blank oscillator plate I26.- is simultaneously moved within the zone: des fined by'its carrier-disc opening I25; Since. the confined zone is somewhat larger in CIOSSi-SEG..- tional area than the cross-sectional area: of: the blank plate, the plate is free.- to move: or rotate within the disc opening. Due to the number of. sides of. each opening and the manner in which they are curvedinwardly, it is d-iflicult to define accurately t'heprecisecourse followed by the plate as the carrier-disc simultaneously pursues. its clockwiseand counter-clockwise courses.

Because of the rapidity with. which lower lap ping head 45 is rotated comparedwiththe rateof rotation of carrier-disc 91 and the further fact that thecarrier-disc has a counter-clockwise. movement, the: dragging counter-clockwise action of the lappingsurface'of the lower lapping. head against the bottom of, each blank plate-tendsrto impart a generally similar counter-clockwise. movement of the plate in its disc'opening. The effect, therefore, is simultaneously to move each blank plate generally in the same direction. of travel. as that of the rotating; lapping surface: in: a path of relatively small convolutions about a. moving point relatively near the center-of the blank plate as the plate advances around. the orbits of the larger'pathsdescribed above.

Unusually good results have been. obtained".

The blank plates are lapped to an; exceedingly smooth finish. This applies to the: edgeportions of: the plates aswell as: to their majorfaces. Also; the present invention provides for the rapid. re"-.- ducing of the quartz oscillator plates tozathicka ness from which they are to-be finished by hand. For example; using 220 grit and rotating: thehead: 45 at 1100 R. P. M. and shaft T0.- at' the rate of approximately R. P. M. the quartz: crystal plates have been reduced in. thickness at: the rate: of approximately .010 inch per minute; The rate of removal of stock Varies depending: on the" size, Much. better" results are obtained according to the present method thancan be obtained, for example, by'th'e method of moving the blank plates solelyby a. carrier-disc. of conventional construction between two sta-- tionary lappin heads. It is believed that the superior results of" the present practice may be in part due to an enhanced reciprocal eifectbetween the lapping surfaces of the lapping blocks and the surfaces of themajor faces of the bl'ank' plates. Because of the exceedingly tortuous, constantly shiftingfpath repeatedly followed by each blank plate, the eflective lapping" surfaces of the lapping blocks aremaintained; uniformly smooth and fiat. Thesmooth: and list surfaces are in turn adapted to lap the major'faces of'tlie blank plates to a smooth and flat. finish.

Having thus set forth. the nature of myinvention, what I claim is:

1. In apparatus for the manufacture of quartz oscillator plates, a base, a lower. vertical spindle. extending above said base, a motor on said base means. to drive; said. spindle from. said motor, a lower lapping head concentric with and. driven. by said. spindle, a carrier disc. disposed on;

- 1.111981 s -e s 9 peme i ee satel te annulus shaped lapping head disposed over said carrier disc, means for holding said upper lapping head substantially stationary, an upright supported from said base at one side of said spindle, a head on said upright and extending radially therefrom over said lower vertical spindle, an upper vertical spindle having bearing in said head and arranged in alignment with the lower vertical spindle, a motor supported from said head, a drive between the'second mentioned motor and the upper vertical spindle, a crank on the lower end of said upper vertical spindle and including a pin located eccentrically with respect to said upper vertical spindle and entering the central opening of said annulus shaped upper lapping head, and a hub centrally located on said carrier disc and receivin the lower end portion of said eccentrically located pin whereby as said upper vertical spindle is rotated said carrier disc is given a satellite movement about the axes of said upper and lower vertical spindles.

2. In apparatus for the manufacture of quartz oscillator plates, a base, a lower vertical spindle extending above said base, a motor supported on said base, means to drive said spindle from said motor, a lower lappin head concentric with and driven by-said spindle, a carrier disc disposed on the upper side of said lower lapping head, an upper annulus shaped lapping head disposed over said carrier disc, means for holding said upper lapping head substantially stationary, an upright supported from said base at one side of said spindle, a head and a motor supported from said upright, said head extending radially from said upright over said lower spindle, a vertical spindle having bearing in said head and arranged in alignment with the lower vertical spindle, a drive between the second mentioned motor and the upper vertical spindle, a crank on the lower end of said upper vertical spindle and including an eccentrically located part entering the central opening of said annulus shaped upper lapping head, a hub centrally located on said carrier disc and receiving the lower end portion of said eccentrically located part, whereby as said upper vertical spindle is rotated said carrier disc is given a satellite movement about the axes of said upper and lower vertical spindles.

3. In an apparatus for the manufacture of quartz oscillator plates, a base, a lower vertical spindle extending above said base, a motor on said base, a pulley and belt drive between said motor and said lower vertical spindle, a lower lappin head concentric with and driven by said lower vertical spindle, a carrier dis disposed on the upper side of said lower lapping head, an

10 upper annulus shaped lapping head disposed on said carrier disc, means for holding said upper lapping head substantially stationary, an upright supported from said base at one side of said lower vertical spindle, a head and a motor supported on said upright, said head extending radially of said upright to a position over said lower vertical spindle, an upper vertical spindle having bearing in said head and arranged in alignment with the lower vertical spindle, a counter shaft supported in said head, a belt drive from said motor to said counter shaft, a variable speed belt drive between said counter shaft and said upper vertical spindle, a crank on the lower portion of said upper vertical spindle and including a part located eccentrically with respect to said upper vertical spindle and entering the opening of said annulus shaped upper lapping head, and a hub centrally located on said carrier disc and receiving the lower end portion of said eccentrically located part whereby as said upper vertical spindle is rotated said carrier disc is given a satellite movement about the axes of said upper and lower vertical pindles.

4. The apparatus as in claim 3 including a quill about and forming a bearing means for a lower portion of said upper vertical spindle, means for shifting said quill and thus said spindle vertically to carry said eccentric part into and out of the central opening of said annulus shaped upper lapping head, and means for locking said quill and thus said upper vertical spindle in the desired position of adjustment.

IRVING S. PRIMUS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,375,003 Kent May 1, 1945 1,610,527 Indge Dec. 14, 1926 2,264,163 Indge Nov. 25, 1941 2,369,107 Indge Feb. 6, 1945 2,352,105 Kent June 20, 1944 1,870,328 Indge Aug. 9, 1932 1,963,884 Budd June 19, 1934 2,308,512 Hoffman Jan. 19, 1943 2,309,080 Hunt Jan. 19, 1943 2,314,787 Hunt Mar. 23, 1943 1,610,984 Van Keuren Dec. 14, 1926 FOREIGN PATENTS Number Country Date 514,794 Germany Dec. 17, 1930 

